5

4

3

2

1

0

-1

0

0.5

1.0

1.5

2.0

2.5

V

(V)

REF

Single-EndedInput

V

=5V

DD

3.8

2.8

2.2

-0.3

0

0.2

5

4

3

2

1

0

-1

0

0.5

1.0

1.5

2.0

2.5

V

(V)

REF

DifferentialInput

V

=5V

DD

3.8

2.75

0.95

-0.3

3.0

2.5

2.0

1.5

1.0

0.5

0

-0.5

-1.0

0.10

0.35

0.60

0.85

1.10

1.35

V

(V)

REF

Single-EndedInput

1.5

1.5

1.05

-0.2

V

=2.7V

DD

0.5

0.2

3.0

2.5

2.0

1.5

1.0

0.5

0

-0.5

-1.0

0

0.25

0.50

0.75

1.00

1.25

V

(V)

REF

DifferentialInput

V

=2.7V

DD

1.5

1.5

0.5

-0.3

0

ADS8317

www.ti.com .................................................................................................................................................... SBAS356D – JUNE 2007 – REVISED OCTOBER 2009

Figure 38. Single-Ended 5V Input,

Figure 40. Differential 5V Input,

Common Voltage Range vs VREF

Common Voltage Range vs VREF

Figure 39. Single-Ended 2.7V Input,

Figure 41. Differential 2.7V Input,

Common Voltage Range vs VREF

Common Voltage Range vs VREF

When the input is differential, the amplitude of the

In each case, care should be taken to ensure that the

input is the difference between the +IN and –IN input,

output impedance of the sources driving the +IN and

or +IN – (–IN). A voltage or signal is common to both

–IN inputs are matched. If this matching is not

of these inputs. The peak-to-peak amplitude of each

observed, the two inputs could have different settling

input is VREF about this common voltage. However,

times. This difference may result in offset error, gain

since

the

inputs

are

180°

out-of-phase,

the

error, and linearity error that change with both

peak-to-peak amplitude of the difference voltage is 2

temperature and input voltage. If the impedance

× VREF. The value of VREF also determines the range

cannot be matched, the errors can be lessened by

of the voltage that may be common to both inputs, as

giving the ADS8317 additional acquisition time.

shown in Figure 41 and Figure 40.

Copyright © 2007–2009, Texas Instruments Incorporated

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